Thinking as I so often do about Typology, particularly in this Rosary Month, and especially about the biblical typological basis of devotion to our Lady, I am wondering if anyone can help me out with information about that lovely invocation in the Litany of Our Lady, Turris eburnea, ora pro nobis.
The litany of our Lady (of Loretto), we learn from standard reference books, is first found in the sixteenth century and bears a close family resemblance to a number of late fifteenth century litanies to her. We know, too, that Tower of Ivory appears to be derived from the Song of Songs, where the beloved bride is said to have a neck like a tower of ivory.
In 1957, writing about Eucharistic Reservation, two theologians (SJP van Dijk and J Hazelden Walker) discuss the practice, common in the first millennium, of keeping the Blessed Sacrament in a tower made of ivory; the tower being designed to resemble what was taken to be the appearance of the Sepulchre in which the Lord's body rested. They write: 'the purity and whiteness of ivory was much favoured. Up to the present day, this preference is preserved in the litany of the blessed Virgin, who is invoked as the Tower of Ivory'. They make this statement obiter and without references.
My problem is that as far as I am aware, this method of Reservation did not survive until the middle of the second millennium. So was the idea of vD and HW just an attractive guess? Or is there evidence for this title being used of our Lady in the centuries before the sixteenth? I would very much like to believe these writers. The symbolism of relating our Lady, as 'container' of his natural body, to the vessel within which his sacramental Body is kept, is, surely, devotionally very attractive.